Refactor code generation to allow us to diff generic expressions and not just fields

third_party/WebKit/Source/build/scripts/templates/fields/field.tmpl

 {% macro encode(field, value) %}
 {% if field.is_bit_field -%}
 static_cast<unsigned>({{value}})
 {%- else -%}
 {{value}}
 {%- endif %}
 {% endmacro %}
 
 {% macro decode(field, value) %}
 {% if field.is_bit_field -%}
@@ skipping 69 matching lines @@
     {{subgroup.member_name}} = other.{{subgroup.member_name}};
   {% elif subgroup.fields|select("in", fields_to_copy)|list|length > 0 -%}
     {{fieldwise_copy(subgroup, fields_to_copy)}}
   {% endif %}
 {% endfor %}
 {% for field in group.fields|select("in", fields_to_copy) -%}
   {{setter_expression(field)}} = other.{{getter_expression(field)}};
 {% endfor %}
 {% endmacro %}
 
-{% macro fieldwise_diff(group, fields_to_diff) %}
-{% for subgroup in group.subgroups %}
-{% if subgroup.all_fields|select("in", fields_to_diff)|list|length > 0 -%}
-if ({{subgroup.member_name}}.Get() != other.{{subgroup.member_name}}.Get()) {
-{{fieldwise_diff(subgroup, fields_to_diff)|indent(2, true)}}
+{% macro fieldwise_diff(groups_to_diff) %}

[shend, 2017/05/11 05:00:59]

Would this be easier if you took in a single group (i.e. the root DF)? Like move
up a level of recursion. Something like the original jinja code:

fieldwise_diff(df)
  for subgroup in df.subgroups
    fieldwise_diff(subgroup)
  endfor
  for expr in df.exprs
  endfor
  

[nainar, 2017/05/11 06:00:08]

Done.

+{% for group in groups_to_diff %}
+if ({{group.group_name}}.Get() != other.{{group.group_name}}.Get()) {
+{% if group.subgroups %}
+{{fieldwise_diff(group.subgroups)|indent(2, true)}}
+{% endif %}
+{% for expression in group.expressions %}
+  if ({{expression}} != other.{{expression}})
+    return true;
+{% endfor %}
 }
-{% endif -%}
-{% endfor %}
-{% for field in group.fields|select("in", fields_to_diff) %}
-if ({{getter_expression(field)}} != other.{{getter_expression(field)}})
-  return true;
 {% endfor %}
 {% endmacro %}